So, we wrote our own.
It is a standard WordPress Plugin. All you need to do is unzip the file to your plugins directory, or use the zip file upload feature. Once you've installed it, simply activate. There are no special settings or anything else you need to do.
To embed an InfusionSoft web form into a post or page, use the following short code:
[infusionsoft_form src="<Your form's url>"]